Since his wife passed away, Shang Yuan (played by Ha Zhengyu) has become more and more distant from his daughter, so he decided to move to the countryside with his daughter to repair their relationship. But even after moving, Shang Yuan still focused on his work and didn't pay much attention to his daughter. His daughter had more time alone and began to show strange and disturbing behavior, and Shang Yuan began to encounter strange phenomena at home. One day, his daughter suddenly disappeared in front of the closet without a trace... No matter how Shang Yuan looked for her, he couldn't find her. At this time, a man named Qingxun (played by Kim Nam-gil) suddenly came to the door and claimed that he knew the secret of the closet. In order to find Shang Yuan's daughter, Qingxun insisted that Shang Yuan break into the "middle ground" with him, so the two began to uncover the unspeakable truth hidden behind the closet...